[Johnny555]

I can think of two times in my life where I even considered the possibility that one of my peers would do something malicious on their way out the door, but management worries about this all the time.

Proper offboarding protects you too, not just the company. If you leave the company and someone compromises one of the 27 hard-coded credentials left behind on various machines and services, then it puts you under suspicion.

In companies where I do have hard coded creds (including shared passwords), when leaving a company, I compile a list of all of them and send it to my manager and tell them to make sure they are all disabled.

[ghaff]

Yep. It's like sharing passwords to important personal accounts more generally. Sure, the main reason you don't is that stuff can happen in relationships and people can end up doing things you didn't think they would. But a secondary reason that if something does happen in an account that you've shared a password with someone, it's hard not to have at least a glimmer of suspicion.